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