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