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