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