I suggest you start by thinking what time of year you want to hatch eggs. You will need room to brood the chicks when they hatch, too.
Putting all the chickens together for the winter can work just fine, if you do not intend to hatch eggs in the winter.
You just need to separate them into appropriate breed groups 3-4 weeks before you are ready to start collecting eggs for hatching.
Or, let them run together for most of the winter, then move the roosters to a bachelor pad a month before you want to hatch. Put the right hens with the right roosters at least two days before you collect eggs.
Or, as Ridgerunner suggested, leave one rooster in with the hens and put the other roosters in the bachelor coop. Set eggs only from the hens of the same breed as the rooster, and only if it's been at least 3 weeks since the hens last had access to the other roosters.