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