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