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