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