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