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