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