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