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