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