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