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