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