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