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