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