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