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