  We construct a new family of trivalent expanders tessellating hyperbolic
surfaces with large isometry groups. These graphs are obtained from a family of
Cayley graphs of nilpotent groups via $(\Delta-Y)$-transformations. We compare
this family with Platonic graphs and their associated hyperbolic surfaces and
see that they are generally very different with only one hyperbolic surface in
the intersection. Moreover, we study combinatorial, topological and spectral
properties of our trivalent graphs and their associated hyperbolic surfaces.
