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