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