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