I got better actual colors on my corals when I supplemented my LEDs with 2 T5 bulbs. I say actual colors because you can have the appearance of better colors with blue and purple LEDs, but the corals will not really change, only your perception of those colors.
If you want the corals to actually get better coloration, you need more actual usable light for them. T5 lights will provide this for them. This is just my two cents and based on my personal experience.