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