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