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