WordNet (r) 3.0 (2006):

protective coloration
    n 1: coloration making an organism less visible or attractive to
         predators

Moby Thesaurus II by Grady Ward, 1.0:

23 Moby Thesaurus words for "protective coloration":
   aggressive mimicry, apery, camouflage, cryptic mimicry, disguise,
   domino, false colors, false face, false front, incognito, mask,
   masque, masquerade, mimicry, mockery, mummery, parrotry,
   playing possum, smoke screen, synaposematic mimicry, visor, vizard,
   vizard mask