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