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