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