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