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