It just so happens I'm making a game with some sprites called 'orb1' and 'orb2' right now. I'm also using a lot of WebGL including colour changes.
You could try applying the WebGL effect called "AdjustHSL" and have the hue altered depending on whatever it is in your game that determines the 'orb' colour. The other way would be to avoid WebGL and simply have a set of animations for the sprite that you can switch for each instance, depending on your parameters.
Haha, that's a nice coincidence!
But, problem is: I don't know how to apply these effects! I've looked everywhere (not everywhere, because I didn't find anything).