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