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