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