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