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