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