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