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