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