Just clean it normally--if you're other coworkers see you, then say you spilled coffee on it.

Go to the websites below on how to clean it or just remove odors from it.

PS-If your chair doesn't smell to the normal person--i.e. you only smell it when you bend down and put your face up to it to take a whiff--then I would just leave it. It's better to have a chair that smells like poop (but not one will actually smell it unless they put their face next to it) rather than a suede chair that you tried to clean and wound up funny looking because you ruined the leather. Suede is apparently really tricky to clean (I've never tried it) so you may want to take that into consideration.