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