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