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