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