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