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