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