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