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