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