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