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