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