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