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