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