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