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