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