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