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