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