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