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