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