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