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