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