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