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