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