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