It depends on the person mostly. "Congrats on your award" is most common. But sometimes you will see "Congrats for". I think you usually see "for" used when it's something they did. "congrats for winning" but "congrats on winning" is also common. You rarely see "congrats for your award".
"Congrats to" would be used when the speaker is talking to a group and not just the person they are congratulating.
"Congrats to George for winning the game"