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