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