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