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