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