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