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