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