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