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