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