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