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