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