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