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