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