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