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