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