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