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