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