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