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