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