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)(27,31,28,33)(29,34,37,39)(35,38,36,40)(1,2,5,6)(3,7,8,4)(10,11)(15,17)(16,18)(22,23)(25,27)(26,31)(28,30)(29,35)(32,33)(34,38)(36,37)(39,40)(1,2)(3,7)(4,8)(5,6)(10,11)(12,19)(13,21)(22,23)(26,32)(27,28)(29,37)(38,40) involution — undirected(2,6)(3,8)(9,11,14,10)(12,15,19,17)(13,18,21,16)(20,22,24,23)(25,28,30,27)(26,33,32,31)(29,35,37,36)(34,38,39,40)(1,3)(2,4)(5,8)(6,7)(9,12)(10,15)(11,17)(13,20)(14,19)(16,22)(18,23)(21,24)(25,29,30,37)(26,34,32,39)(27,35,28,36)(31,38,33,40)(1,4)(2,3)(5,7)(6,8)(9,13,14,21)(10,16,11,18)(12,20,19,24)(15,22,17,23)(25,26)(27,31)(28,33)(29,34)(30,32)(35,38)(36,40)(37,39)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.