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)(27,31)(28,34)(29,33)(30,32)(35,37)(36,40)(38,39)(3,8)(6,7)(9,11)(10,15)(12,19)(13,17)(14,18)(16,23)(20,21)(22,24)(26,27)(29,37)(32,34)(36,38) involution — undirected(1,3,5,8)(2,6,4,7)(11,18)(12,20)(13,15)(16,24)(25,27,31,26)(28,34,30,32)(29,35,37,33)(36,40,38,39)(3,8)(6,7)(9,11)(10,15)(12,21)(13,17)(14,18)(16,22)(19,20)(23,24)(25,28,31,30)(26,32,27,34)(29,36,37,38)(33,39,35,40)(1,3)(2,7)(4,6)(5,8)(9,12)(10,16)(11,19)(13,22)(14,20)(15,23)(17,24)(18,21)(25,29,31,37)(26,33,27,35)(28,36,30,38)(32,39,34,40)(1,4,5,2)(3,6,8,7)(9,13,14,15)(10,11,17,18)(12,22,20,23)(16,19,24,21)(25,30,31,28)(26,34,27,32)(29,38,37,36)(33,40,35,39)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.