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