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