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