  A graph is called a GRR if its automorphism group acts regularly on its
vertex-set. Such a graph is necessarily a Cayley graph. Godsil has shown that
there are only two infinite families of finite groups that do not admit GRRs :
abelian groups and generalised dicyclic groups. Indeed, any Cayley graph on
such a group admits specific additional graph automorphisms that depend only on
the group. Recently, Dobson and the last two authors showed that almost all
Cayley graphs on abelian groups admit no automorphisms other than these obvious
necessary ones. In this paper, we prove the analogous result for Cayley graphs
on the remaining family of exceptional groups: generalised dicyclic groups.
