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