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