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