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)(15,16)(17,22)(18,24)(19,23)(20,21)(25,27)(26,28) involution — undirected(5,6)(7,10)(8,9)(11,12)(13,15,17,21,19,26,18,25)(14,20,24,16,23,27,22,28)(2,4)(6,9)(10,12)(13,16,17,27,19,28,18,20)(14,21,24,26,23,25,22,15)(6,9)(10,12)(13,17,19,18)(14,22,23,24)(15,25,26,21)(16,27,28,20)(5,7,8,11)(6,10,9,12)(14,23)(15,26)(21,25)(22,24)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.