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