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