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