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