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