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