In substance painter, I went ahead and painting the color map for my chameleon. It took me while to develop a design that looked believable and appealing. Originally I was going for a more colorful chameleon pattern, but after multiple unsuccessful attempts, I tried a more subtle and natural approach as seen in my two references below. I was pleased with this new approach.
Additionally I adjusted the roughness and height of the scale pattern and added a wrinkle texture to the chin. Once that was done I exported my color, roughness, normal, height, and scattering maps and plugged them into my Maya shader. I was having problems with the displacement of the scale pattern on my model even after I increased my iterations, I wasn't getting a detailed result, so I decided to go without and compensate with the bump value instead. Above is my most recent beauty render for my chameleon. I noticed however that I need to go back and adjust the interior of the chameleon's mouth. The color needs to be fleshier and pink and should have very little roughness, so I'll go in and adjust that soon, so that I can get ready to render out my animation for compositing later this weekend.