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