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