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