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