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