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