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