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