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