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