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