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