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