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)(11,16)(12,18)(13,14)(15,17)(19,23)(20,24)(21,22)(25,26,31,35)(27,30,36,32)(28,37,39,33)(29,34,40,38)(3,7)(5,8)(9,11)(10,16)(12,19)(13,15)(14,17)(18,23)(20,21)(22,24)(25,27,31,36)(26,32,35,30)(28,29,39,40)(33,34,37,38)(1,2)(3,5)(4,6)(7,8)(10,17)(11,13)(12,20)(22,23)(25,28,31,39)(26,33,35,37)(27,29,36,40)(30,38,32,34)(9,12,15,20)(10,18,17,24)(11,19,13,21)(14,22,16,23)(25,28)(26,33)(27,29)(30,38)(31,39)(32,34)(35,37)(36,40)(1,3)(2,5)(4,7)(6,8)(9,13,15,11)(10,14,17,16)(12,21,20,19)(18,22,24,23)(25,29)(26,34)(27,28)(30,37)(31,40)(32,33)(35,38)(36,39)(1,2)(3,5)(4,6)(7,8)(9,14)(10,11)(12,22)(13,17)(15,16)(18,19)(20,23)(21,24)(25,30,31,32)(26,27,35,36)(28,38,39,34)(29,37,40,33)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.