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