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