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