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