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