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