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