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