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