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