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)(13,14,17,19)(15,22,25,28)(16,21,18,27)(20,24,23,26)(6,9)(10,12)(14,19)(20,23)(21,27)(22,28) involution — undirected(13,15,16,24,17,25,18,26)(14,20,27,28,19,23,21,22)(2,4)(13,14)(15,23)(16,27)(17,19)(18,21)(20,25)(22,24)(26,28) involution — undirected(5,7,8,11)(6,10,9,12)(13,16,17,18)(14,21,19,27)(15,24,25,26)(20,22,23,28)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.