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