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