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