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