First, let's get the dullest one I've found out of the way. This is actually a sculpture that was found on the Arizona Museum of Natural history website. Dull does not necessarily mean bad and that is true here. Anatomically this sculpture is perfect and the feathering is quite detailed head to toe with the exception of the chicken legs and hardened beak being bare of feathers. Here the tail possesses one fan of feathers directly at the end of the tail pointing, if the tail were straight, directly backward or away from the body of the animal. The coloring of the animal is also unique in regard to other representations of the dinosaur. Personally, while I love the idea of these animals wildly colored and highly tropical looking, I believe that this color scheme would provide more camouflage and thus be more likely, unless Caudipteryx is like modern birds and this color scheme was a strictly feminine trait while the outlandish colors and brightness in the next illustrations were more of a masculine thing to tote out into the world.
Luis Rey had a very different approach to Caudipteryx. He made the animal very noticeable in a green world. In this background, because of the flowers, it is less noticeable even with the brilliant colors. This is a very likely evolutionary step, in all actuality, because flowering plants had only come about a million years prior and therefore, with flowers suddenly arriving on the scene, it would be to any animal's benefit if they could manage to hide in plain sight with the new flowers. Feathers adapting to be brilliantly colored in like the flowers would have made for an amazing set of fauna during this time period. Even the face of the animal is heavily colored and is also quite avian in appearance, not unlike the faces Oviraptors appear with. However, I am going to stick with the male/female coloration traits as my theory because I believe that birds and dinosaurs are related closely and we can back up that coloration theory heavily with examples from our time; birds from the peafowl to the cardinal to wood ducks are heavily dimorphic species. Here, also, we find the tail of Caudipteryx is shown in a fan pattern, but split in a "V" down the middle of the tail on the top side of the tail. This could, though, be an aggressive or mating posture of the tail feathers, or could even be, like the coloring, a male trait that would not exist in female Caudipteryx.
This illustration, done for the Australian Museum by James Reece, shows the non-split tail fan and less feathering than most other illustrations. The tail fan here is held rigidly out and up like a peacock's tail. The arm feathering is also a great deal smaller than most of the other illustrations that turn up in a search. Both of these add up to artist's choice, as does the way the skull was portrayed. Like in the previous illustration, this face is mostly bare rather than heavily feathered, however, this skull has an earthy coloration to the skin of the face and is more reptilian than bird-like. The lock of black feathers behind the eyes makes the face almost mammalian actually, as though it were a balding man maybe, or covered in the same way that other primate's heads are covered even with the face bare. It still has chicken legs as well.
This last illustration for today accentuates the avian nature of Caudipteryx. Tucciarone's illustration possesses many avian qualities that have been shown in other illustrations- namely feathering, the chicken legs, the tail fan, and a wing-like arm- but also possesses reptilian qualities in the head at the same time. Here, though, we have an animal in the midst of a hunt for insects. The very attack on the insect, which looks like a cross between a dragonfly and a common house fly, is very avian in nature and not reptilian, which is what most dinosaurs are depicted as during the hunt, though as more active reptiles than simple ambush hunting reptiles. This Caudipteryx, however, is leaning in, actively chasing the insect and has spread its arms or wings and tail fan for balance while giving chase which, growing up with chickens, I have seen many times in birds at a full run (or waddle, chickens running look funny and it's more of a waddling motion). The posturing of this piece is fantastic if it is agreed that Caudipteryx was heavily avian, though, as we know, not everyone sees things that way.