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