Funny thing is, if you compare competition pics, these guys look 10-15 years older than they actually are!
I noticed this with Levrone, he looks like he's in his 20 now, when he competed he looked like late 30s.
When i saw Coleman from close, i was astonished about how good his skin really looked. He looked better than most 40 years olds.
Even if roids and the extreme conditions before competitions would make you look older, the huge amounts of GH would also have their effect to keep the body younger in a way.
Either way, being a professional bodybuilder is not the healthiest thing you can do in your life.