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