One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,4)(5,6)(7,9)(8,10)(11,12) involution — undirected(6,9)(7,12)(10,11)(13,14)(15,21)(16,19)(17,20)(18,23)(22,27)(24,26)(25,28) involution — undirected(2,4)(13,15,17,23)(14,18,20,21)(16,24,25,22)(19,27,28,26)(6,10)(9,11)(13,16,17,25)(14,19,20,28)(15,22,23,24)(18,26,21,27)(14,20)(18,21)(19,28)(26,27) involution — undirectedA Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.