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