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