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