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