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