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