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