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