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