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