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