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