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