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