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