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