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