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)(12,16)(13,15)(14,18)(19,24)(20,23)(21,22)(25,26,31,28)(27,34,32,29)(30,36,38,33)(35,37,39,40)(1,3,5,8)(2,6,7,4)(9,11,15,12)(10,16,13,17)(14,19,22,20)(18,23,21,24)(25,26,31,28)(27,34,32,29)(30,33,38,36)(35,40,39,37)(1,3)(2,4)(5,8)(6,7)(9,11,15,12)(10,17,13,16)(14,19,22,20)(18,24,21,23)(25,27)(26,29)(28,34)(30,35)(31,32)(33,37)(36,40)(38,39)(1,4)(2,3)(5,6)(7,8)(9,12,15,11)(10,17,13,16)(14,19,22,20)(18,23,21,24)(25,28,31,26)(27,34,32,29)(30,33,38,36)(35,37,39,40)(9,13,15,10)(11,16,12,17)(14,21,22,18)(19,23,20,24)(25,29,31,34)(26,32,28,27)(30,37,38,40)(33,39,36,35)(9,14)(10,18)(11,19)(12,20)(13,21)(15,22)(16,23)(17,24)(25,30,31,38)(26,33,28,36)(27,35,32,39)(29,37,34,40)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.