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