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