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