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