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