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