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