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