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