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