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