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