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