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