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