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