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