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