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