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