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