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