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