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