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