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