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