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