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)(15,23)(16,18)(17,20)(19,22)(21,25)(24,26)(27,28) involution — undirected(1,2)(3,4)(6,10)(11,12)(13,15,18,25)(14,21,16,23)(17,28,22,24)(19,27,20,26)(5,7,9,8)(6,11,10,12)(13,16,20,17,18,14,19,22)(15,24,27,21,25,28,26,23)(2,4)(5,8,9,7)(6,12,10,11)(13,17,20,14,18,22,19,16)(15,21,27,28,25,23,26,24)(6,10)(11,12)(14,16)(17,22)(21,23)(24,28) 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.