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