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