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