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