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