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