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