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