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