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