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