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