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