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)(13,14,18,19)(15,20,16,17)(22,26)(24,27)(5,6)(7,10)(8,9)(11,12)(14,19)(15,16)(22,26)(23,28) involution — undirected(6,9)(10,12)(13,15,18,16)(14,20,19,17)(21,22,25,26)(23,27,28,24)(1,2)(3,4)(5,7,8,11)(6,10,9,12)(13,16,18,15)(14,20,19,17)(21,23)(22,27)(24,26)(25,28)(5,6)(7,10)(8,9)(11,12)(13,17,18,20)(14,15,19,16)(21,24,25,27)(22,23,26,28)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.