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