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