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