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