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