Just ask a question about the person, people are almost always happy to talk about themselves. Something not too personal, and ideally related to something present--i.e. if there's something going on in the kitchen or whatever. In the most general case, you're in a coworking space and their ostensibly working for a company there, so "Hey, I noticed you around and was curious about what your company does?" is generally pretty easy. Or if it's obvious what their company does, "Hey I noticed you around and I was curious about what you do at Foo Company?"
Don't overthink it, it's just a conversation and the worst that happens is you return to the awkward silence that was there before.