According to this article the answer is: exactly like us.
WHAT WILL “SPACE PEOPLE” LOOK LIKE?
by Willy Ley
Condensed from This Week Magazine
A short time ago man put artificial satellites in space. Sometime in 1958 we will launch a piloted aircraft into space. Some scientists are confident we could hit the moon with an unmanned rocket today. Within 10 or 20 years spaceflight will be an almost everyday occurrence.
Once we are in space, the question arises â€” will we be the only ones? Will we find other intelligent beings plying the spaceways, and if so. what will they be like? We cannot predict everything, of course, but we do have a good idea of what space people might look like.