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