One vertex per element, one color per generator, with an edge from x to x·s.
(2,3)(5,6)(7,10)(8,9)(11,12) involution — undirected(1,2,4,3)(6,9)(10,12)(13,14)(15,22)(16,18)(17,20)(19,23)(21,25)(24,28)(26,27)(1,3,4,2)(5,7,8,11)(6,10,9,12)(14,18)(16,25)(19,22)(20,21)(23,26)(27,28)(13,15,17,24)(14,19,20,27)(16,26,25,23)(18,22,21,28)(14,20)(18,21)(19,27)(22,28) 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.