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