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