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)(11,18)(12,16)(13,22)(14,17)(15,20)(19,24)(21,23)(25,26,32,29,31,35,30,40)(27,36,28,38,37,33,39,34)(3,8)(5,7)(9,11)(10,15)(12,19)(13,21)(14,20)(16,23)(17,18)(22,24)(25,27)(26,33)(28,32)(29,34)(30,39)(31,37)(35,36)(38,40) involution — undirected(1,3,4,8)(2,5,6,7)(9,12,14,13)(10,16,17,22)(11,19,20,21)(15,23,18,24)(25,28)(26,34)(27,30)(29,36)(31,39)(32,37)(33,40)(35,38)(2,6)(5,7)(11,20)(15,18)(19,21)(23,24)(25,29,32,35,31,40,30,26)(27,34,28,36,37,38,39,33)(9,13,14,12)(10,16,17,22)(11,21,20,19)(15,23,18,24)(25,30,31,32)(26,29,35,40)(27,28,37,39)(33,38,36,34)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.