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