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