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