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