One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,5)(4,6)(7,8)(9,10)(11,18)(12,16)(13,22)(14,17)(15,20)(19,24)(21,23)(25,26,29,32,28,31,36,39)(27,33,35,40,34,30,37,38)(1,3)(2,5)(4,7)(6,8)(9,11)(10,15)(12,21)(13,19)(14,20)(16,24)(17,18)(22,23) involution — undirected(2,6)(3,7)(25,27,29,35,28,34,36,37)(26,30,32,38,31,33,39,40)(2,6)(5,8)(9,12,14,13)(10,16,17,22)(11,19,20,21)(15,23,18,24)(26,31)(27,34)(32,39)(35,37)(9,13,14,12)(10,16,17,22)(11,19,20,21)(15,24,18,23)(26,31)(30,33)(32,39)(38,40)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.