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