This patio was more than likely made with concrete pavers, not a specific type of stone. Concrete pavers come in many sizes, styles, colors, and designs so many people can customize their look.

Based on the picture, this patio looks to be made out of Bluestone Select set in a random pattern. Bluestone Select is a type of bluestone that has only grays/blue stones throughout each stone. If you are trying to match this, be careful not a purchase Bluestone Full Color, because then you will have grays, blues, tans, and browns.

You can also get some similar colors in porcelain pavers these days which will even have highlights like mica flecks. Porcelain has the advantage in that it has virtually zero water absorption so doesn't suffer and freeze/thaw issue and resists staining.