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