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