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