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