As mentioned above, water quality, diet, and tankmates affect coloration to an extent. What many fail to realize is genetics play a HUGE role in what a fish looks like. The best we can do is feed the highest quality foods available.
That said, I feed my Orinos a mix of Massivore, algae wafers (little secret...spirulina is a godsend for coloration), NLS pellets, shrimp, and tilapia, and my guys are blinged out.