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