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