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