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)(13,14)(15,22)(16,18)(17,21)(19,24)(20,25)(23,27)(26,28) involution — undirected(5,7,8,11)(6,9,10,12)(14,18)(15,23)(16,25)(19,22)(20,21)(24,28)(2,4)(13,15,16,23,17,24,25,28)(14,19,18,26,21,22,20,27)(6,10)(9,12)(15,24)(19,22)(23,28)(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.