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