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