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