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