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