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