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