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