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