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