Granular crystals are periodic structures of elastic beads arranged in crystal lattices. One important feature of granular crystals is that the interactions between beads can take place via noncentral contact forces, leading to the propagation of rotational and coupled rotational-translational waves. Here, we theoretically demonstrate the topological properties of these mechanical rotational waves in a granular graphene, a two-dimensional monolayer honeycomb granular crystal with Dirac dispersion at the center of the Brillouin zone. Around the Dirac point, effective spin, helicity, and effective spin-orbit coupling are illustrated in the mechanical granular system. Finally, quasitopological transport, where the rotational edge waves are nearly topologically protected, is observed on the interface.