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