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