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