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