First things first - remember that if you place red/blue/green pellet on top of pink/yellow/cyan shard (and vice versa) then it will replace them by pushing out the previous color. That's the main gimmick of that puzzle.
I don't remember which color opens the door, but you if you will choose yellow/cyan version, then all you need to do is to replace most of the colors by the gimmick i explaned earlier - you can do it with a red fei pellet which wonders around right side of the screen (place red pellet on top of cyan shard - then do the same by placing a pellet of needed secondary color on top of now red shard), after that there will be at most only one shard of wrong color which you'll need to "fix" by color combining.