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