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