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