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