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