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