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