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