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)(11,19)(12,22)(13,17)(14,18)(15,21)(16,23)(20,24)(27,29)(32,34)(35,37)(39,40)(1,2)(3,5)(4,6)(7,8)(9,11,14,21)(10,15,18,19)(12,20,23,13)(16,24,22,17)(25,26,31,28)(27,34,29,32)(30,33,38,36)(35,40,37,39)(9,10,14,18)(11,15,21,19)(12,16,23,22)(13,17,20,24)(25,27,31,29)(26,32,28,34)(30,35,38,37)(33,39,36,40)(1,3,4,7)(2,5,6,8)(9,10)(11,15)(12,16)(13,17)(14,18)(19,21)(20,24)(22,23)(25,28,31,26)(27,32,29,34)(30,36,38,33)(35,39,37,40)(9,12)(10,16)(11,20)(13,21)(14,23)(15,24)(17,19)(18,22)(25,29,31,27)(26,32,28,34)(30,35,38,37)(33,40,36,39)(9,13,14,20)(10,17,18,24)(11,12,21,23)(15,16,19,22)(25,30)(26,33)(27,35)(28,36)(29,37)(31,38)(32,39)(34,40)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.