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