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