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