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