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)(27,37)(28,34)(29,31)(30,39)(32,36)(33,40)(35,38)(3,7)(5,8)(10,16)(11,12)(18,21)(19,20)(25,27)(26,33)(28,30)(29,38)(31,39)(32,40)(34,35)(36,37) 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)(25,28,32,29)(26,34,36,31)(27,30,40,38)(33,35,37,39)(1,3)(2,5)(4,7)(6,8)(9,12,15,11)(10,17,16,14)(13,20,23,19)(18,24,21,22)(25,29,32,28)(26,34,36,31)(27,38,40,30)(33,35,37,39)(1,2)(3,5)(4,6)(7,8)(9,13,15,23)(10,18,16,21)(11,19,12,20)(14,22,17,24)(25,30,32,38)(26,35,36,39)(27,28,40,29)(31,33,34,37)(9,14,15,17)(10,11,16,12)(13,22,23,24)(18,19,21,20)(25,31,32,34)(26,29,36,28)(27,39,40,35)(30,33,38,37)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.