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