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