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