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