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