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