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