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