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)(11,20)(12,13)(14,19)(15,17)(16,22)(18,23)(21,24)(26,30)(27,33)(32,38)(34,35)(1,3,5,8)(2,6,4,7)(9,11,15,22)(10,16,17,20)(12,19,18,24)(13,21,23,14)(25,26)(27,31)(28,32)(29,30)(33,37)(34,39)(35,40)(36,38)(1,4,5,2)(3,7,8,6)(10,17)(12,18)(16,20)(19,24)(25,26,29,30)(27,31,33,37)(28,32,36,38)(34,39,35,40)(9,12,15,18)(10,13,17,23)(11,19,22,24)(14,16,21,20)(25,26)(27,31)(28,32)(29,30)(33,37)(34,39)(35,40)(36,38)(9,13)(10,18)(11,21)(12,17)(14,22)(15,23)(16,24)(19,20)(25,27)(26,31)(28,35)(29,33)(30,37)(32,40)(34,36)(38,39) involution — undirected(9,14,15,21)(10,19,17,24)(11,13,22,23)(12,16,18,20)(25,28,29,36)(26,32,30,38)(27,34,33,35)(31,39,37,40)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.