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