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