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