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