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