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