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