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