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