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