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