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