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