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