*However*...if you don't know this already, kittens in the same litter can have different fathers. In fact, it's technically possible for every single kitten in a litter to have a different father...
Plus, you can't necessarily just go on color. If a kitten is orange, it *could* have come from the orange tom you know about...or it could have come from a completely different orange tom. Cats are like that.
Just wanted to add that I agree with the above poster said. I've got a litter of 4 siblings. The mother was calico. Out of the 4, one is a classic light Grey tabby, one has a cream undercoat with Grey stripes over top, one is dark Grey and white, and one is calico.
Had a litter of six with a tortoiseshell mother. Of the 6, 2 were red, one was cream and white, once was a calico, and 2 were tortoiseshell. We kept the 4 siblings, and kept the calico girl from the litter of 6. (I take in and hand raise orphaned kittens during the summers)