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