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