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