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