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