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