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