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