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