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