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