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