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