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