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