  Let $A$ be a finite-dimensional gentle algebra over an algebraically closed
field. We investigate the combinatorial properties of support $\tau$-tilting
graph of $A$. In particular, it is proved that the support $\tau$-tilting graph
of $A$ is connected and has the so-called reachable-in-face property. This
property was conjectured by Fomin and Zelevinsky for exchange graphs of cluster
algebras which was recently confirmed by Cao and Li.
