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