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