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