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