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