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