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