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