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