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