I'd say give it another month or two and you may start to see some color coming in. This is my first experience owning a synspillum so can't really say for sure. But I think around the 3" mark is when mine started coloring up. They are a gorgeous fish when adults. Look at this pic of an exceptional adult I found on the web.
Mine eats just about anything. I feed a staple of Omega One cichlid pellets and NLS. He also gets sinking shrimp pellets, Spirulina flake (while he's still small), assorted frozen foods (bloodworms, brine shrimp and krill), chopped fresh market shrimp and he loves zucchini and shelled peas. Oh yeah, I also have some sun dried river shrimp I occasionally feed.