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