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