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