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