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