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