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