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