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