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