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