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