Peruse the available paint brush colour options for each species of Neopet. (It's our own version of the Neopets Rainbow Pool.) You can even see a list of which ones haven't been released yet!
Prior to 2007's big revamp, Neopet colour combos were available in static poses, which you can see below:
Close Attack, Left
Close Attack, Right
Ranged Attack, Left
Ranged Attack, Right