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