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