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