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