Would it be better if i redesigned this small light to use seperate LEDs for each color? I cant add anymore LEDs because of space so it would be like dividing the amount of LEDs by 4. I could also connect them in series etc and group their anodes together so i can use either an NPN transistor or the same type of mosfet that you showed in your diagrams.

The only problem with using seperate LEDs is the color mixing. The idea is that they combine to make loads of colors. When the light is shining at an object then its not so bad but these small ones are designed to be pointed at people. I think from a distance the colors should mix alright