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