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