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