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)(15,23)(16,18)(17,21)(19,24)(20,25)(22,26)(27,28) involution — undirected(1,2)(3,4)(6,9)(10,12)(13,15,17,24)(14,19,21,23)(16,20,22,28)(18,27,26,25)(5,7,8,11)(6,10,9,12)(13,16,26,21,17,22,18,14)(15,19,27,28,24,23,25,20)(2,4)(13,15,18,25,17,24,26,27)(14,20,22,23,21,28,16,19)(6,9)(10,12)(14,21)(16,22)(19,23)(20,28) 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.