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