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)(15,23)(16,17)(18,22)(19,21)(20,24)(25,28)(26,27) involution — undirected(5,6,9,10)(7,11,8,12)(13,15,19,24)(14,20,21,23)(16,25,26,18)(17,22,27,28)(1,2,3,4)(5,7,9,8)(6,11,10,12)(14,21)(15,24)(16,26)(22,28)(1,2)(3,4)(5,7,9,8)(6,11,10,12)(13,16)(14,17)(15,25)(18,24)(19,26)(20,22)(21,27)(23,28)(5,8,9,7)(6,12,10,11)(13,17)(14,16)(15,22)(18,23)(19,27)(20,25)(21,26)(24,28)(13,18,19,25)(14,22,21,28)(15,16,24,26)(17,20,27,23)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.