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