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