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