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)(11,16)(12,20)(13,18)(14,15)(17,22)(19,21)(23,24)(25,26)(27,31)(28,33)(29,34)(30,35)(32,36)(37,39)(38,40)(2,3)(6,7)(10,15)(11,19)(17,20)(18,24)(25,27)(26,31)(28,37)(29,38)(30,36)(32,35)(33,39)(34,40) involution — undirected(1,3,5,2)(4,7,8,6)(10,15)(11,19)(17,20)(18,24)(27,36)(31,32)(37,40)(38,39)(1,4,5,8)(2,6,3,7)(9,11,14,19)(10,16,15,21)(12,18,22,24)(13,17,23,20)(25,27)(26,32)(28,37)(29,39)(30,36)(31,35)(33,38)(34,40)(9,12,14,22)(10,17,15,20)(11,18,19,24)(13,16,23,21)(25,28)(26,33)(27,37)(29,35)(30,34)(31,39)(32,38)(36,40)(9,13,14,23)(10,18,15,24)(11,20,19,17)(12,21,22,16)(25,29,30,33)(26,34,35,28)(27,38,36,39)(31,40,32,37)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.