There we were with a large group all keen for Cosmic Encounter. It was a delightful sensation until I realised we were seven strong and only had six colours.
It was easy enough to use traditional playing cards or coasters for planets and quarters or bottle caps for tokens, but the real issue was destiny cards. Well somebody came up with the bright idea to use the special destiny cards as the seventh colour. While I am a big fan of special destiny it was even nicer to get to include everybody. It was a fantastic game too, I might write a session report on BGG.
One more thought - you can do this to add an eighth player post Conflict - simply designate one of the specials to trigger the Hazard deck.