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