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