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