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