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