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