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