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)(15,16)(17,28)(18,26)(19,25)(20,24)(21,27)(22,23) involution — undirected(5,7,8,11)(6,9,10,12)(13,15,19,22)(14,21,25,28)(16,24,23,26)(17,20,27,18)(6,10)(9,12)(13,16,19,23)(14,22,25,15)(17,26,27,24)(18,28,20,21)(2,4)(13,17,18,15,19,27,20,22)(14,23,24,21,25,16,26,28)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.